<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <script src="https://cdn.jsdelivr.net/npm/vue/dist/vue.js"></script>
    <style>
        .ball {
            width:15px;
            height:15px;
            background-color: red;
            border-radius: 50%;
        }
    </style>
</head>
<body>
    <div id="app">
        <button @click="flag=!flag">动画</button>
        <transition
        @before-enter="beforeEnter"
        @enter="enter"
        @after-enter="afterEnter">
            <div class="ball" v-show="flag"></div>
        </transition>
    </div>
    <script>
        var vm = new Vue({
            el:'#app',
            data:{
                flag: false
            },
            methods:{
                beforeEnter(el){
                    el.style.transform = 'translate(0, 0)';
                },
                enter(el, done){
                    el.offsetWidth;
                    el.style.transform = 'translate(150px, 350px)';
                    el.style.transition = 'all 1s ease';
                    done();
                },
                afterEnter(el){
                    this.flag = !this.flag;
                }
            }
        });
    </script>
</body>
</html>